Aims: We present a study of the envelope morphology of the carbon Mira R For with VLTI/MIDI. This object is one of the few asymptotic giant branch (AGB) stars that underwent a dust-obscuration event. The cause of such events is still a matter of discussion. Several symmetric and asymmetric scenarios have been suggested in the literature. Methods: Mid-infrared interferometric observations were obtained separated by two years. The observations probe different depths of the atmosphere and cover different pulsation phases. The visibilities and the differential phases were interpreted using GEM-FIND, a tool for fitting spectrally dispersed interferometric observations with the help of wavelength-dependent geometric models. Results: We report the detection of an asymmetric structure revealed through the MIDI differential phase. This asymmetry is observed at the same baseline and position angle two years later. The observations are best simulated with a model that includes a uniform-disc plus a Gaussian envelope plus a point-source. The geometric model can reproduce both the visibilities and the differential phase signatures. Conclusions: Our MIDI data favour explanations of the R For obscuration event that are based on an asymmetric geometry. We clearly detect a photocentre shift between the star and the strongly resolved dust component. This might be caused by a dust clump or a substellar companion. However, the available observations do not allow us to distinguish between the two options. The finding has strong implications for future studies of the geometry of the envelope of AGB stars: if this is a binary, are all AGB stars that show an obscuration event binaries as well? Or are we looking at asymmetric mass-loss processes (i.e. dusty clumps) in the inner part of a carbon-rich Mira?

So far, the most promising theory for the existence of subdwarf B (sdB) stars is that they were formed during binary star evolution. This research was conducted to test this theory by searching for companions around six sdB pulsators (V391 Peg, HS 0702+6043, EC 20117-4014, PG 1219+534, PG 0911+456, and PG 1613+426) using the Observed-minus-Calculated (O-C) method. A star’s position in space will wobble due to the gravitational forces of any companion. If the star is emitting a periodic signal, the orbital motion of the star around the system’s center of mass causes periodic changes in the light pulse arrival times. After obtaining the O-C diagrams for these stars, useful limits on suspected companions’ minimum masses and semimajor axes were calculated. In addition, “period vs. amplitude” and “mass vs. semimajor axis” modeling were conducted to investigate the ranges and combinations of possible companion masses and semimajor axes that are consistent with the observational data. For V391 Peg and HS0702+6043, companions noted in previous publications validated the method used in this research and confirmed their existence. The results of this study of both these targets yield the same masses and semimajor axes as the published ones, within the uncertainties. For EC20117-4014, current data show that there is a companion and the signal of a companion candidate was detected with higher than 90% of confidence level. However, there is still several possible mass and semimajor axis combinations of the companion star. For PG1219+534, current data suggest that there may be a companion, however, the no-companion possibility still cannot be eliminated. The results of this project discovered two new possible companion candidates to EC20117-4014 and PG1219+534, confirmed companions previously detected in V391 Peg and HS0702+6043, as well as provided preliminary evidence for companions to EC20117- 4014 and PG1219+534 at the will require further observation. Though still a small sample, these results suggest that planets might survive the post-main-sequence evolution of their parent stars.

Numerical modelling of the HD 115600 system to try and figure out if a planet is causing the observed eccentricity/offset of the debris disc. Best fit is a 7.8 Jupiter mass planet at 30 AU in an eccentric e=0.2 orbit.

Several imaged substellar companions previously classed as "brown dwarfs" might be included in Extrasolar Planet Encyclopaedia according to latest "exoplanet-VLM star" divide (i.e. m < 61 Mj). Here are some but the list is much longer:

The distant brown dwarf component of ξ UMa is assigned the letter D in the WDS catalogue, C seems to be optical (Raghavan et al. 2010). Unhelpfully, D has also been used to represent the secondary component of the B subsystem (which would be more systematically called Bb). There are several pieces of evidence that suggest that Bb is actually a star in a nearly face-on orbit: the rotational velocity of Ba suggests a low inclination (assuming Ba is tidally-locked to Bb) and from the system dynamics an additional 0.5 solar masses is needed in addition to Ba to bring the B subsystem up to the correct mass, see Griffin (1998). The claimed third star in the B subsystem (Bc) has never been seen again since the original discovery observations.

Lazarus wrote:The distant brown dwarf component of ξ UMa is assigned the letter D in the WDS catalogue, C seems to be optical (Raghavan et al. 2010). Unhelpfully, D has also been used to represent the secondary component of the B subsystem (which would be more systematically called Bb). There are several pieces of evidence that suggest that Bb is actually a star in a nearly face-on orbit: the rotational velocity of Ba suggests a low inclination (assuming Ba is tidally-locked to Bb) and from the system dynamics an additional 0.5 solar masses is needed in addition to Ba to bring the B subsystem up to the correct mass, see Griffin (1998). The claimed third star in the B subsystem (Bc) has never been seen again since the original discovery observations.

Lazarus wrote:The distant brown dwarf component of ξ UMa is assigned the letter D in the WDS catalogue, C seems to be optical (Raghavan et al. 2010). Unhelpfully, D has also been used to represent the secondary component of the B subsystem (which would be more systematically called Bb). There are several pieces of evidence that suggest that Bb is actually a star in a nearly face-on orbit: the rotational velocity of Ba suggests a low inclination (assuming Ba is tidally-locked to Bb) and from the system dynamics an additional 0.5 solar masses is needed in addition to Ba to bring the B subsystem up to the correct mass, see Griffin (1998). The claimed third star in the B subsystem (Bc) has never been seen again since the original discovery observations.

CS 1246 is a hot subdwarf B star discovered in 2009 to exhibit a single, large-amplitude radial pulsation. An O-C diagram constructed from this mode revealed reflex motion due to the presence of a low-mass M dwarf, as well as a long-term trend consistent with a decrease in the pulsational period. The orbital reflex motion was later confirmed with radial velocity measurements. Using eight years of data collected with the Skynet Robotic Telescope Network, we show that the pulsation amplitude of CS 1246 is decaying nonlinearly. We also present an updated O-C diagram, which might now indicate a positive P˙ and a new 2.09±0.05 yr oscillation consistent with orbital reflex motion of the entire inner sdB+dM binary, possibly due to the gravitational influence of a circumbinary planet with minimum mass msini=3.3±2.11.2 MJup. However, unlike the presence of the M dwarf, we hesitate to claim this object as a definitive detection since intrinsic variability of the pulsation phase could theoretically produce a similar effect.